NTSB finds rudder problem in Airbus-300 (AA Flight 587)

Washington Times ^ | June 1, 2004 | staff

[Boot Hill]

WASHINGTON, DC, May. 29 (UPI) -- An investigation into the November 2001 crash of an Airbus A-300-600 in New York has found an unrelated potentially lethal design flaw, the New York Times reports.

The newspaper says the National Transportation Safety Board does not believe that problems with the rudder control system caused the crash of American Airlines Flight 287 [should be: 587]. The plane came down shortly after taking off from Kennedy International Airport en route to the Dominican Republic, killing all 260 people on the plane and five on the ground.

[Boot Hill]

Other stories on this breaking news can be found at:

Crash probe uncovers flaw in Airbus jet

--Boot Hill

[Dog Gone]

During its investigation, the NTSB examined an earlier incident involving an American Airlines Airbus-300 that lost 3,000 feet in height.

That's one tall plane.

[Sloth]

Yes, the rudder tends to stick when in proximity to a shoe bomb.

[adam_az]

I was at LaGuardia waiting to fly home to AZ when I saw that crash on the TV... Went right to the bar and ordered a drink.

[Boot Hill]

"Yes, the rudder tends to stick when in proximity to a shoe bomb."

Only problem with that theory is that there is ZERO post-crash forensics that supports that possibility.

--Boot Hill

[Ichneumon]

[During its investigation, the NTSB examined an earlier incident involving an American Airlines Airbus-300 that lost 3,000 feet in height.]

That's one tall plane.

Not nearly as tall as it *used* to be, apparently...

Someone smack this reporter and editor until they learn the difference between "altitude" and "height".

[theDentist]

It's designed to be that tall so it can more effectively land on those runways
that are 300 feet long and 2 miles wide.

[The KG9 Kid]

I have a future Uncle-in-law who was an American Airlines pilot of 31 years. He follows NTSB/FAA stories closely, and fully expected that they'd correctly rule American Airlines Flight 587 had it's tailplane ripped off due to a known design flaw that Airbus has been trying to downplay in the market.

He and others believe that Airbus cannot correct the flaw without a major redesign. Planes already in service cannot be retrofitted with the correction.

[Dog Gone]

ROFL

[Ichneumon]

Only problem with that theory is that there is ZERO post-crash forensics that supports that possibility.

Shh, don't interrupt a conspiracy theorist with facts, it just confuses them.

[Blood of Tyrants]

Since the A-300 is a fly-by-wire, i.e. a computer translates an input from the yoke and pedals to an electrical signal to an actuator, this would simply be a programming change.

[COEXERJ145]

Just like with every crash of an Airbus built aircraft, Airbus will not accept blame and will turn around and blame the pilots and airline.

[Sloth]

Only problem with that theory is that there is ZERO post-crash forensics that supports that possibility.

Oh, I don't really think that's what brought it down. But I enjoy suggesting it, because of how officials always downplay or reject the possibility of terrorism before the fires are even out.

[Sloth]

See #13.

[Dan(9698)]

The vertical stabalizer came off.

After loss of rudder control, it went into a spin, the spin made it shed parts all over the streets below, and crash.

Rudder control is what keeps an airplane from spinning. (invented by the Wright Brothers to keep their airplane from spinning.)

[DuncanWaring]

... a known design flaw ...

Composite/carbon fiber delamination?

[tbeatty]

Since the A-300 is a fly-by-wire, i.e. a computer translates an input from the yoke and pedals to an electrical signal to an actuator, this would simply be a programming change.

Not quite. Part of the equation is the rate of response of the actuator and this could be related to air pressure on the airfoil as well as it's structural requirments.

There may not be a solution that meets NTSB requirements as well as the stability and structural requirements of the rudder.

[pitinkie]

Exactly

[COEXERJ145]

Since the A-300 is a fly-by-wire, i.e. a computer translates an input from the yoke and pedals to an electrical signal to an actuator, this would simply be a programming change.

Actually the A300 and its smaller sister the A310 are not fly-by-wire. The A320 family (A318/319/320/321), A330-200/300, 340-200/300/500/600, and the new A380-800 are FBW.

[RandyRep]

I don't think the delamination was the primary cause -- it was a result of the design defect, and resulted in the failure of the vertical tail and subsequent loss of the aircraft.

Reading between the lines, I think this is what happened during the flight: the aircraft flew through a wind gust or wind shift that quickly increased the airspeed (relative to the wind) to a level above that allowed for the low speed rudder setting.

For example (and I don't know the exact numbers here), at airspeeds below say 180 KIAS, the allowable rudder deflection might be 30 degrees. Above say 180 KIAS, the allowable rudder deflection might be 15 degrees. At higher airspeeds, say 250 KIAS, the allowable rudder deflection might be 10 degrees. Since rudder force is proportional to the square of the velocity, the maximum allowable deflection at a given airspeed is set so as to provide sufficient yawing moment but not allow excessive yawing moment.

If the airplane was flying at say 175 KIAS and the pilot moved to maximum deflection of 30 degrees, the flight control system would command 30 degrees and the vertical tail and rudder would be below the maximum allowable loads. If a wind shift occurred during or after this rudder deflection, and the airspeed increased to say 250 knots, the rudder, which is still deflected at 30 degrees, would cause a high yawing moment and the load on the vertical tail might be above the allowable maximum load. The pilot might try to compensate by turning the rudder in the opposite direction which might exacerbate the flight upset. This might cause failure of the rudder and departure of the rudder from the aircraft and subsequent aircraft crash.

I postulated this theory at work (an aircraft component manufacturer - I'm an aerodynamics engineer) and on one of the crash boards after the crash. It's good to see it proven out.